Primer



J 30, 1940 c. E. RICHARDSON PRIMER Filed Sept. 3, 1937 2 Sheets-Sheet 1FIG. 2

FIG. 3

INVENTOR. CREIGHTON E. RICHHRDSON.

A TTORNEY Jan. 30, 1940- c. E. RICHARDSON PRIMER 2 SheetsSheet 2 FiledSept. 3, 1937 INVENTOR. CRE/G-HTON E. RICHARDSON.

A TTORNEY Patented :Jan. 30, 1940 Creighton Elliott Richardson,Brownsburg, Quebec, Canada, assignor to Canadian Industries Limited, acorporation of Canada Application September 3, 1937, Serial No. 162,234In Canada September 5, 1936 6 Claims.

formed in the plate which is in intimate contactwith the detonatingcomposition in the primer cup and. serves as a support against which the10 detonating composition is driven by the impact of the firing pin.Means had to be provided whereby the flash of the detonating compositioncould pass around or past. the anvil and through the flash hole of thecartridge case to the propellent charge. Numerous methods. have beenproposed for forming the flash passages in the anvil and the meansgenerally adopted in the industry have been to remove a semi-circularsection from the plate on opposite sides of the apex.

This method however had several disadvantages. The removal-of theopposite semi-circular portions of the anvil leave the anvil radiallyweakened and subject to easy distortion when being pressed into theprimer cup onto the detonating composition. The semi-circular openingsare also very difiicult to seal with lead foil and practicallyimpossible to seal with varnish. Lead foil as heretofore used could notform an efllcient seal because of two distinct disadvantages of the an-3o vils oi the prior art. Prior art practice comprised shearing a discof foil from a sheet placed over the primer cup plate by the downwardmovement of a punch, the inner edge of the primer cup acting as ashearing edge against the periphery of 5 the punch. The anvil was thenpressed into position above the foil, but because of the semicircularsections removed from the edge of the prior art anvils, the foil lackedadequate support at these points and-also because of the re- 40 moval ofthese semi-circular sections the cutting of the foil disc could not beperformed in the anvil seating operation as is possible with the primerof my invention. Prior art anvils, not

being completely circular, are liable to cause se- 45 rious distortionof the primer cup which, when not perfectly circular, is not easilyfitted into the recess of the cartridge case.

An object of the present invention is to provide an anvil for use inprimers for ammunition 50 having eiflcient and adequate flash passageswithout the mechanical strength of the anvil being materially weakened.A further object is the production of an anvil having flash passageswhich are easily sealed with a disc of lead foil 5 or by means ofvarnish and a still further object is the production of primers in whichthe possibility of en masse" explosions is considerably reduced. Furtheradvantages will be apparent from the following description.

These objects are attained with the pierced ani 5 vii of my invention inconjunction with the efllcient means of sealing the flash passages thereof with heat-fusible material as more particularly described withreference to the accompanying drawings in which the same numerals areused to '10 designate like parts in all the figures and in which Figure1 is a plan view of the anvil made according to my invention.

Figure 2 is a cross-sectional view of Figure 1 on the line BB.

Figure 3 is a cross-sectional view o'f a primer cup complete with theanvil of my invention, the detonating composition and the lead foil forsealing the detonating composition beneath the anvil.

Figure 4 is a diagrammatic cross-sectional view showing the meansusedfor simultaneously assembling the anvil and heat-fusible disc in theprimer cup, as well as the cutting of the disc of heat-fusible material.

In Figure 1 the flash holes are shown at l, and 2 is the apex of theanvil. While I have shown only two flash holes, I have also producedanvils having three holes and four holes. I have found in fact that thenumber and size of the holes are 3' limited only by the available areaof the anvil and that all the advantages of my invention are attainedwith any number of holes of any size within that limitation. I prefer touse only two flash holes however, since I have found that adequate flashpassage is obtained with two holes and production of the anvil issomewhat more simple than with three or 'four holes. The round holes asshown may be either drilled or punched but it is obvious that the holesneed not be round. and could be made in any other shape and remainwithin the scope of my invention since an essential feature of myinvention is that the formation of flash passages be made between theinitial rise of the apex and the circumference of the anvil withoutconverging into the circumference of the anvil and with no encroachmentor only slight encroachment into the initial rise of the apex. This ismore clearly shown in' Figure 2 which is a cross-section on the line BBor Figure 1. As shown the anvil has a flat base and slightly roundedshoulders 6, both of which features facilitate the centering of theanvil as will be more fully described hereinafter. The apart 2 is shownas having a rounded contour but the s5 configuration of the apex is notclaimed as an essential feature oi my invention. For example, a'nvilshave been proposed having the apex of various configurations such ascones, truncated cones, pyramids and truncated pyramids and it isobvious that my invention could be used with any of these. I havereferred above to the fiat base and rounded shoulders of my anvil andwhile neither of these features are new in themselves, such features, inconjunction with the fully circular base give a further improvement inthe facility with which my anvil is inserted in the primer cup. Therounded shoulder is also of itself of advantage in sealing thedetonating composition with the anvil of my invention.

Discs of lead foil or other heat-fusible material, have been generallyused for such sealing, the disc being pressed into place over thedetonatingcomposition and the anvil then pressed into place about thesealing disc. By this method the detonating composition was firstpressed to a compact mass in the bottom of the priming cup. By analternative method the pressing of the detonating composition and thepressing into place of the sealing disc was done simultaneously by thepressing punch. Efllcient sealing by either of these methods was notobtained however, when using the an'vils hitherto known to the art asdescribed above. The indentation left by removal of the semi-circularsections left these sections of the anvil without adequate support forthe lead foil discs at these points and the foil discs thus had atendency to fold or collapse at these points either when placing theanvil in position or in the subsequent operations of completing theprimer or in the handling of the completed shells. The very smalldiameter of the sealing discs also made it diflicult to insure that thedisc was properly centered over the detonating composition. The primersin which the disc were not properly centered were therefore verysusceptible to en masse" explosions since in such primers a partial areaof the detonatlng composition would remain uncovered. This failure toobtain a proper seal is one of the serious disadvantages of using theanvils hitherto known to the art. A further disadvantage of theimperfectly sealed primer is the possibility of loss of detonatlncomposition and the consequent reduction of flash qualities of theprimer, and a still further disadvantage is the failure to obtainadequate moistureprooflng. Adequate sealing by the use of varnish wasalso unobtainable with the anvils hitherto available for the samereasons.

The efllcient sealing obtained with anvils made according to myinvention is clearly illustrated in Figures 3 and 4 in which V3 is theprimer cup, 4 is the detonating composition, 5 is the lead foil 'orother sealing disc, 8 are the shoulders of the anvil and '5 shows thelead foil or other heat-fusible material conforming to the contour ofthe shoulders.

In Figure 4 is shown a diagrammatic crosssection of the plates used inassembling the anvils in the primer cups and the method ofsimultaneously cutting the foil disc and seating the anvil referred toabove. The anvils are shaken on the plate 8 having opening ittherethrough adapted to support the anvil as shown. The priming cups 3are likewise shaken on plate 8 until cups come to rest in each of thecavities l l. Each plate hasf aplurality of cavities, andthe cavities ofthe plate are adapted to position themselves in vertical axial alignmentwith the cavities of the primer cup plow when the anvil plate issupermsed on the primer cup plate. Punches which I shall refer tohereinaiter as anvil seating punches are shown at A, B, C, D, E, F, andG. The first five of these it A to E inclusive are shown in theirinoperative position. The use of thetwo plates with the anvil seatingpunches is well known in the prior art practice and is not claimed as anessential feature of my invention. primers according to my inventionhowever, I interpose a sheet of lead foil or other heatfusible sheetmaterial between the anvil plate and the primer cup plate.

Seating of the anvil into the primer cup with 115 the anvil apex inintimate contact with, and slightly embedded in the detonatingcomposition is attained by downward movement of the anvil seating punchand it is in this operation when performed according to, and withthe'anvil of 29 my invention, that emcient protection against en masse"explosions is obtained. It will be apparent in Figure 4 that the anvilmust pass through the heat-fusible sheet material and this is moreclearly shown with the anvil-seating 25 punches F and G. Downwardmovement of the anvil-seating punch F brings the anvil apes: 2 intocontact with the sheet or heat-fusible material. The downward movementof the anvilseating punch being continuous the height of 34$ the anvilapex above its shoulder is such that the contacting of the anvil apexwith the foil is immediately succeeded by contact of the shoulder of theanvil with the heat-fusible material and almost simultaneous contactbetween heat- 35 fusible material and the inner periphery of the primercup. The downward pressure of the apex on the heat-fusible material thuscauses the latter to stretch but this stretching is almost immediatelyresisted by the simultaneous pe riphery contacts referred to above Thisinitial resistance causes the anvil apex to pierce the heat-fusiblematerial and this piercing is immediately successive to the peripheralcontacts referred to above. The anvil apex then serves as a centeringguide for the foil in the remainder of the operation. The peripheralcontacts being simultaneous, a shearing edge is formed between theperiphery of the anvil and the periphery of the primer cup and theheat-fusible material being between the shearing edges is cut in a disc.Since the diameter of the cavity in'the primer cup is slightly greaterthan the diameter of the anvil at the termination of the roundedshoulder, the base of the sheared disc in its conical form will in turnbe of slightly greater diameter than the anvil. This slight excess indiameter allows conformity of the sheared disc to the rounded shoulderof the anvil in its continued downward progress in the primer cup andconfines the margin of the disc in the tapering recess between therounded shoulder and the cup well, thus insuring a tight seal at theperiphery of the anvil. Due to the method of assembly, as heretoforedescribed, the disc has a large area of close contact with the peripheryof the anvil apex; thus the disc seals and covers the flash holes withan impermeable membrane bybeing sealed effectively at the edge portionat the rounded shoulder and at the edge portion When producing 1o lowersurface of the sealing material and the interior of the cup containingthe primer mixture. As can be seen from the drawings, the anvil is thenadvanced into the cup in such a manner as to approximately reduce thevolume by with a corresponding increase of pressure in accordance withthe relation P1V1=P2V2 further causing the sealing material to moveagainst the anvil and assuming the shape thereof.

This eflicient protection against en masse explosions is particularlynecessary when using the modern priming compositions. A mixture ofmercury fulminate and potassium chlorate was former-ly used as thepriming composition for small arms ammunition primers. When a number ofprimers loaded with this mixture were stored or handled together theexplosion of one was sumcient to communicate the explosion to the othersin the container, but this resulted in a number of small individualdetonations which were not particularly hazardous. With most othercompositions and especially the more modern priming compositionshowever, for example, those containing lead styphnate, the explosion ofone is very likely to cause the simultaneous explosion of all the otherprimers in the container and the resulting explosion is therefore ofconsiderable intensity. Such explosions, commonly termed en masseexplosions are prevented by the provisions of my invention. It will alsobe apparent that misfires caused by loss of priming composition areconsiderably reduced if not completely eliminated by the efficient andadequate sealing attained by my invention. Alternatively the lead foilor other heat-fusible material maybe omitted and the holes may be sealedby the use of a varnish or lacquer or any other moistureprooffilm-forming fluid. Since the flash holes are relatively small, being ofabout inch diameter for small arms ammunition anvils, adequate supportis obtained whether foil or fluid is used.

Having thus described my invention what I' claim is:

1. A primer for ammunition comprising a primer cup, a primingcomposition in said cup, an. anvil having an unbroken peripheral contactwith said cup, an apex on said anvil projecting toward said primingcomposition, flash passages in said anvil between said apex and saidunbroken periphery; and an impermeable membrane in continuouscircumferential contact with the surface of said anvil apex, coveringsaid flash passages "and held in sealing engagement with said anvil atthe periphery thereof.

2. A primer for ammunition comprising a primer cup, 8. primingcomposition in said cup. an anvil having an-unbroken peripheral contactwith said cup, an apex on said anvil projecting toward said primingcomposition, flash passages in said anvil between said apex and saidunbroken periphery; and an impermeable membrane covering said flashpassages and held in sealing engagement with said anvil at the peripherythereof.

8. In a primer for ammunition, the combination with a primer cup and apriming mixture in said cup; of an anvil comprising a flat base havingflash passages therethrough, a continuous periphery for engagement withsaid cup, an inwardly rounded shoulder merging with said continuousperiphery, and a substantially centrally disposed apex projecting fromsaid base; and an impermeable membrane covering said flash passages andsealed at said rounded shoulder between said anvil and said cup.

4. A priming for ammunition comprising a primer cup a primingcomposition in said cup, an anvil having an unbroken peripheral contactwith said cup, an apex on said anvil projecting toward said primingcomposition, flash passages in said anvil between said apex and saidunbroken periphery; and a sheet of fusible metal in continuouscircumferential contact with the surface of said anvil apex, coveringsaid flash passages from said sheet, and simultaneously seating saidanvil in said cup and disposing said disc of sealing material in sealingengagement with said anvil and said cup. 6. In the assembling ofammunition primers, the method which comprises interposing a sheet offusible metal between a primer cup and an anvil to be seated in saidcup, advancing said anvil to engage said sheet to first depress aportion thereof into said cup and thereafter shear a disc from saidsheet by the engagement of the periphery of said anvil with theperiphery of said cup, the continued advance of said anvil seating saidanvil in said cup with the margin of said sheet in sealing engagementwith said anvil and said cup at the contactv surfaces thereof.

CREIGHTON E. RICHARDSON.

